Pneumovirinae viruses are negative-sense, single-stranded, RNA viruses that are responsible for many prevalent human and animal diseases. The Pneumovirinae sub-family of viruses is a part of the family Paramyxoviridae and includes human respiratory syncytial virus (HRSV). Almost all children will have had an HRSV infection by their second birthday. HRSV is the major cause of lower respiratory tract infections in infancy and childhood with 0.5% to 2% of those infected requiring hospitalization. The elderly and adults with chronic heart, lung disease or those that are immunosuppressed also have a high risk for developing severe HRSV disease (http://www.cdc.gov/rsv/index.html). No vaccine to prevent HRSV infection is currently available. The monoclonal antibody palivizumab is available for immunoprophylaxis, but its use is restricted to infants at high risk, e.g., premature infants or those with either congenital heart or lung disease, and the cost for general use is often prohibitive. In addition, nucleoside analog ribavirin has been approved as the only antiviral agent to treat HRSV infections but has limited efficacy. Therefore, there is a need for anti-Pneumovirinae therapeutics.